Combined vessel dissection and transection device and method

ABSTRACT

A retractor and a surgical tool are positioned within a cannula, and a dissection cradle of the retractor is positioned at the distal end of the cannula. The retractor includes a first portion with an axis approximately parallel to the axis of the cannula and a second portion with an axis skewed relative to the axis of the cannula. The dissection cradle is located at the distal end of the second portion of the retractor, and may include two substantially parallel, spaced legs with the retractor shaped in a loop between and in a plane skewed relative to the axes of the legs, and with the loop directed away from the surgical tool. Thus, in operation, when the surgeon locates a vessel and side branch of interest, the surgeon extends the retractor to cradle the vessel in the dissection cradle. Once cradled, the retractor may be fully extended to urge the vessel away from the axis of the cannula to isolate the side branch for exposure to the surgical tool. Removable, transparent tips are selectively positioned at the distal end of the cannula for performing dissection and transection via a single cannula. Additionally, the tips are configured to align the apices of the tips with the central axis of the endoscope to maximize the visual field through the tips via the endoscope. Wing-like protrusions on an alternate tip for the cannula facilitate tissue dissection in forming a tunnel in tissue along a target vessel. Swept back forward edges on the wing-like protrusions promote easy tissue dissection using reduced force to advance the cannula and alternate tip through tissue surrounding the target vessel.

RELATED APPLICATIONS

This is a continuation of application Ser. No. 09/227,393 filed on Jan.8, 1999, now abandoned which is incorporated by reference herein in itsentirety.

CROSS-REFERENCE TO RELATED APPLICATION(S)

The present application is a continuation-in-part application ofapplication Ser. No. 09/102,723 filed on Jun. 22, 1998, now U.S. Pat.No. 5,895,353, and the subject matter hereof is related to the subjectmatter of application Ser. No. 08/593,533 entitled “TISSUE SEPARATIONCANNULA” filed Jan. 24, 1996 by Albert K. Chin now abandoned, which is acontinuation-in-part application of application Ser. No. 08/502,494,entitled “TISSUE SEPARATION CANNULA AND METHOD.” filed on Jul. 13, 1995,now abandoned, which prior applications are assigned to the sameassignee as the present application.

FIELD OF THE INVENTION

This invention relates to a cannula used for vessel retraction, and moreparticularly to a cannula and method for performing both vesseldissection and transection.

BACKGROUND OF THE INVENTION

One important component of a surgical cannula is the tip, disposed onthe distal end of the cannula. A properly configured tip can provideimportant functionality to a cannula. For example, the functions ofvessel dissection and transection are commonly performed by two separateinstruments. The device described in the pending application Ser. No.08/907,691, entitled “Tissue Separation Cannula with Dissection Probeand Method,” filed on Aug. 8, 1997 now U.S. Pat. No. 5,980,549,discloses a device for separating surrounding connective tissue from avessel (dissection). The device described in the pending applicationSer. No. 09/102,723, entitled Vessel Isolating Retractor Cannula andMethod”, filed on Jun. 22, 1998, discloses a device for retracting thevessel, ligating side branches, and transecting the branches to allowremoval of the vessel. It is desirable to use a single device forperforming the above functions.

The construction of a cannula tip also affects the visual field providedto a surgeon through an endoscope. When an endoscope is situated in alumen of the cannula, the surgeon looks through the endoscope andthrough the transparent tip to view the surgical site. It is desirableto have a tip which maximizes the visual field of the endoscope.

The cannula tip may also be used to dilate a tunnel or anatomical spacethrough tissue planes. In pending application Ser. No. 09/133,136, nowabandoned entitled “TISSUE DISSECTOR APPARATUS AND METHOD,” filed Aug.12, 1998, assigned to the same assignee as the present application, andwhich is hereby incorporated by reference, a cannula is constructed witha bulbous element near the tip of the cannula for performing tissuedilation as the cannula is advanced. Cannula tips for dilating tunnelsthrough tissue require force in order to advance the cannula and dilatethe tissue. It is desirable to have a tip which can perform tissuedilation or dissection using a minimal amount of force and causingminimal trauma.

SUMMARY OF THE INVENTION

In accordance with the present invention, a tissue retractor ispositioned within a cannula with a dissection cradle end of theretractor positioned at the distal end of the cannula. The retractorincludes a first portion that has an axis approximately parallel to acentral axis of the cannula, and a second portion that has an axis whichis at an angle with respect to the central axis of the cannula. Thedissection cradle is located at the distal end of the second portion ofthe retractor. In another embodiment, the retractor includes two legshaving substantially parallel axes that selectively protrude from thedistal end of the cannula. The protruding legs support the dissectioncradle formed in the shape of a loop that is positioned in a planeskewed relative to the axes of the legs, with a bottom of the loopdirected away from the cannula. Thus, in operation, when the surgeonlocates a vein and side branch of interest, the surgeon extends theretractor to cradle the vein in the dissection cradle. Once cradled, theretractor may be fully extended to urge the vein away from the axis ofthe cannula, causing the side branch to be isolated and exposed to asurgical tool. The surgical tool may then be extended from within thecannula to operate on the isolated and exposed side branch.

In another embodiment, the top of the loop of the dissection cradle isflat and thin, allowing atraumatic support of the vein, and minimizingcontact between the retractor and the surgical tool. In yet a furtherembodiment, the retractor includes a single leg with the loop formed bythe one leg of the retractor, and with a stopper coupled to the distalend of the retractor. In still another embodiment, the cannula comprisesa sliding tube which encases the retractor, and in a first position isextended out to encase the second portion of the retractor, and in asecond position is extended to encase only the first portion of theretractor. In response to the sliding tube being in the first position,the second and first portions of the retractor are both approximatelyparallel to the axis of the cannula. In response to the sliding tubebeing in the second position, the second portion of the retractor isskewed relative to the axis of the cannula.

In accordance with an alternate embodiment of the present invention, aremovable, transparent tip is positioned at the distal end of thecannula to provide a single cannula for performing dissection andtransection. When attached, the tip seals the distal end of the cannulain a fluid resistant manner. The tip is conical and ends in a sharpinterior point and a slightly rounded exterior point which allows thesurgeon to bluntly dissect tissue in the area of interest underendoscopic visualization. When tissue dissection is complete, thesurgeon can remove the tip from the cannula, and the surgeon is now ableto use the cannula to transect side branches and vessel ends. In orderto maximize the visual field provided by the endoscope, the tip isconfigured to allow the apex of the tip to be aligned with the centralaxis of the endoscope. In one embodiment, a distal end of the tip istilted in an oblique fashion to allow the apex of the tip to align withor near to the central axis of the endoscope. In an alternateembodiment, the conical end of the tip has unequal taper angles relativeto a plane of transition between the cylindrical and conical portions ofthe tip, thus skewing the position of the apex of the tip into alignmentwith or near to the central axis of the endoscope.

In another embodiment, wing-like protrusions are provided about thecannula near the tip to dilate tissue surrounding the vessel ofinterest. In one embodiment, the wing-like protrusions are diametricallyaligned in a planar configuration with tapered forward edges extendingrearward from near the apex of the tip. The planar configuration of thewing-like dilating protrusions near the tip substantially reduces theresistive force encountered during advancement of the cannula throughtissue. The wing-like protrusions are positioned on opposite sides ofthe tip to dissect tissue to form a cavity that may attain a roundcross-section under insufflation, thus providing the same resultanttissue dilation as provided by a solid oval dilator, but with less forcerequired to accomplish the tissue dilation. In an alternate embodiment,the leading edges of the wing-like protrusions are curved in a parabolicconfiguration away from the distal end of the cannula to provide thenecessary dilation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a preferred embodiment of cannula 100showing retractor 112 in an extended position.

FIG. 2a is a cut-away side view of retractor 112 and cannula 100.

FIG. 2b is a top view of retractor 112.

FIG. 3a is a perspective side view of cannula 100 with a sapphenous veinpositioned within the cradle 116.

FIG. 3b is a perspective side view of the distal end 122 of cannula 100in an embodiment in which an endoscope 126 and a surgical tool 120 arepresent and partially extended.

FIG. 3c is a front view of the distal end 122 of cannula 100 in whichthe surgical tool 120 and the retractor 116 are partially extended, andan endoscope 126 is present.

FIG. 4a is a cut-away top view of cannula 100.

FIG. 4b is a cut-away side view of cannula 100.

FIG. 5a is a cut-away view of a sliding tube embodiment of cannula 100in a first position.

FIG. 5b is a cut-away view of the sliding tube embodiment of FIG. 5a ina second position.

FIG. 6a is a cut-away view of an embodiment of cannula 100 having anangling device 140.

FIG. 6b is a cut-away side view of the apparatus illustrated in FIG. 6ain which the retractor 112 is extended and the angling device 140 isactuated.

FIG. 6c is a cut-away side view of the angling device embodiment inwhich the angling device 140 is in a separate lumen from the retractor112.

FIG. 7a is a cut-away side view of a twistable retractor 112 in astraight position.

FIG. 7b is a side view of the retractor 112 of FIG. 7a.

FIG. 7c is a cut-away side view of twistable retractor 112 in a crossedposition.

FIG. 7d is a side view of the retractor 112 of FIG. 7c.

FIG. 8a is a cut-away side view of the handle 104.

FIG. 8b is a cut-away side view of an alternate embodiment of handle104.

FIG. 9a is a side view of cradle 116.

FIG. 9b illustrates a first alternate embodiment of cradle 116.

FIG. 9c illustrates multiple views of a second alternate embodiment ofcradle 116.

FIG. 9d illustrates multiple views of a third alternate embodiment ofcradle 116.

FIG. 9e illustrates multiple views of a fourth alternate embodiment ofcradle 116.

FIG. 9f illustrates multiple views of a fifth alternate embodiment ofcradle 116.

FIG. 9g illustrates multiple views of an embodiment of cradle 116 havinga spur.

FIG. 10a illustrates a top view of an embodiment of the cradle 116 ofFIG. 9c without a “C” ring.

FIG. 10b illustrates a side view of the cradle 116 of FIG. 10a.

FIG. 10c illustrates a top view of the cradle 116 of FIG. 9c with the“C” ring attached.

FIG. 10d illustrates a side view of the cradle 116 of FIG. 10c.

FIG. 11a illustrates a cut-away side view of a tip 1100 in a cannulahousing an endoscope 126.

FIG. 11b illustrates a side view of the tip 1100 isolated from cannula100.

FIG. 12a illustrates a side view of an offset tip 1200 in accordancewith the present invention.

FIG. 12b illustrates a cut-away side view of the offset tip 1200 in acannula 100 housing an endoscope 126.

FIG. 12c illustrates a cut-away side view of an alternate embodiment ofoffset tip 1200.

FIG. 13 illustrates a cut-away side view of an alternate embodiment ofthe offset tip 1300.

FIG. 14a illustrates a perspective side view of the offset tip 1200 andmounting rod 1404.

FIG. 14b illustrates a perspective side view of cannula 100 for housingoffset tip 1200 and mounting rod 1404.

FIG. 14c illustrates a perspective side view of offset tip housing 1424at the proximal end of the cannula 100.

FIG. 14d illustrates a perspective side view of cannula 100 with offsettip 1200 and offset tip housing 1424.

FIG. 14e illustrates a perspective side view of an alternate embodimentof offset tip mount 1424.

FIG. 14f illustrates a cut-away side view of the offset tip mounting1424 of FIG. 14e.

FIG. 15a illustrates a side view of an alternate embodiment of offsettip 1200.

FIG. 15b illustrates a side view of a cannula 100 modified for use withthe offset tip 1200 of FIG. 15a.

FIG. 16 is a flow chart illustrating a method of dissecting andtransecting vessels according to the present invention.

FIG. 17a illustrates a top view of an embodiment of an offset tipdilator 1700 according to the present invention.

FIG. 17b illustrates a side view of the embodiment of offset tip dilator1716 of FIG. 17a.

FIG. 17c illustrates a top view of an alternate embodiment of offset tipdilator 1700.

FIG. 18 is a flow chart illustrating a method of dilating tissue inaccordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates a perspective view of a preferred embodiment ofcannula 100 showing retractor 112 in an extended position. Cannula 100includes an outer housing 102 of bioinert material such as polymed UDthat may be approximately 12″ to 18″ in length. The proximal end of thecannula 100 is disposed in handle 104 that includes a button 106 whichis coupled to retractor 112 for controlling the translational movementof retractor 112 as described in more detail below.

The distal end of the cannula houses a retractor 112, and optionally anendoscope 126 and a surgical tool 120, described below. FIG. 2aillustrates the retractor 112 in more detail. In one embodiment,retractor 112 if formed of resilient wire which has a smooth bendintermediate to a first portion 110 and a second portion 114 of theretractor. The retractor 112 is described as having two portions forease of description, although the retractor 112 may be formed as anintegrated structure. However, retractor 112 may also be manufacturedfrom two separate portions 110, 114 that are coupled together. The firstportion 110 of the retractor 112 is positioned within the cannula 100with the axis 111 of the first portion 110 approximately parallel to theaxis 101 of the cannula 100. The second portion 114 is positioned tobend away from the central axis 101 of the cannula. The angle 117 ofdisplacement between the axis 115 of the second portion and the centralaxis 101 of cannula 100 may be any angle from zero to 180 degrees. Thesecond portion 114 includes a dissection cradle 116 at the distal end ofthe second portion 114. The retractor 112 may be formed of bioinertmaterial such as stainless steel, or a polymer such as nylon orpolyetherimide, or other appropriately strong and resilient plastic. Inone embodiment, the retractor 112 includes a coating for lubrication,insulation, and low visual glare using, for example, parylene or nylon11.

FIG. 2b illustrates the retractor 112 formed with two legs. The legs141, 142 of the retractor 112 at the distal end form the dissectioncradle 116 in a loop or “U” shape, as shown in FIG. 2a. The top portion144 of the U-shaped bend is preferably flattened to provide additionalsurface area for atraumatically supporting a vein 118 or vessel ofinterest. The side arches 128 of the dissection cradle 116 are used forskeletonizing or dissecting the vein from the surrounding tissues, aswell as acting as walls to keep the vessel captured within the arch. Theseveral embodiments of dissection cradle 116 are described in moredetail below.

FIG. 3a illustrates a perspective view of the cannula 100 in accordancewith the present invention with the retractor fully extended, holding asapphenous vein 118, and also illustrates an external surgical tool 120disposed adjacent the cannula 100 for performing a surgical operation,for example, severing a tributary or side branch of the vein 118. Thevein is positioned within the side arches 128 of the cradle 116. Thedissection cradle 116 may be used to cradle a vein, vessel, tissue ororgan of interest, and surgical tool 120 may be any surgical toolsuitable for performing a surgical procedure near the dissection cradle116.

FIG. 3b illustrates a perspective view of cannula 100 in an embodimentin which the surgical tool 120 is positioned within the cannula 100, andan endoscope 126 is present. In this embodiment, cradle 116 preferablyoverlays the endoscope 126 with sufficient clearance to facilitaterelative movements thereof. However, the endoscope may also be locatedadjacent the surgical tool 120. In one embodiment, endoscope 126 ispositioned with cannula 100 to allow a clear field of view uponextension of the retractor 112. Surgical tool 120 is illustrated ascauterizing scissors, used to sever a tributary or side branch of asapphenous vein 118. In this embodiment, surgical tool 120 is maximallydisplaced from the cradle 116 at the cannula end 122. More specifically,as shown in FIG. 3c, the “U”-shaped loop 129 of the cradle 116 isclosest to the surgical tool 120. This ensures that a vein 118 or othertissue of interest is retracted away from the surgical tool 120 tofacilitate manipulating the surgical tool 120 relative to the sidebranch or other tissue.

FIG. 4a is a cut-away top view of cannula 100. The retractor 112 isslidably positioned within minor lumens 113 along the length of thecannula 100 within close tolerances in order to position the retractor112 stably within the cannula 100. For example, in one embodimentretractor legs 141, 142 are approximately 0.045 inches in diameter andthe lumens 113 encasing the legs 141, 142 are approximately 0.080 inchesin diameter, as friction between the legs of the retractor 112 and thelumens 113 holds the retractor stably within the cannula. Thisconfiguration restricts rotational movement of the retractor to providemore stable retraction as compared with conventional retractors. Thelegs 141, 142 of the retractor 112 are formed of flexible, resilientmaterial and are retained within the lumen 113 in substantially straightor flat orientation, but may return to a material bend or curve, asillustrated in FIG. 5a, as the retractor 112 is extended from the distalend of the cannula 100.

The leg 141 of the retractor 112 passes through a sliding gas or fluidseal 130 at the proximal end of the lumen 113. The leg 141 of theretractor 112 passes out of the cannula 100 and into handle 104 forattachment to a slider button 106 for facilitating translationalmovement of the retractor 112 from the proximal or handle end of thecannula 100. However, other types of control devices such as knobs,grips, finger pads, and the like may be linked in conventional ways tothe retractor 112 in order to manually control the translationalmovement of retractor 112. In one configuration, the proximal end of leg141 is bent relative to the axis of the cannula, and the button 106 isattached to the bent position of the leg 141 to facilitate moving thebutton 106 and the retractor 112 translationally under manual control.The button 106 preferably includes lateral grooves to prevent finger orthumb slippage during sliding manipulation of the retractor 112.

Thus, in the operation of a preferred embodiment, a user actuates theslider button 106 to extend retractor 112 out of the lumen 113 at thedistal end of the cannula 100. In one embodiment, the resilientretractor 112 is formed in a smooth bend, as shown in FIG. 2a, andgradually deflects away from the central axis 101 of the cannula 100 asthe retractor is extended. Upon encountering the target vessel or tissueof interest, the vessel is restrained in the cradle 116, and a lateralresilient force is exerted on the target vessel in a direction away fromthe cannula. The vessel in thus pushed away from the axis of the cannula100, isolating if from surrounding tissue or adjacent vessels such astributaries or side branches. As a tributary is thus isolated, asurgical tool 120 such as cauterizing scissors may be safely employed tooperate on the tributary without harming the sapphenous vein 118. Whenretracted into the cannula 100, the retractor 112 is again resilientlystraightened or flattened.

In an alternate embodiment as illustrated in FIGS. 5a and 5 b, a slidingtube 132 is added to provide operational versatility to cannula 100. Ina first position, the sliding tube 132 is retracted and the retractor112 protrudes from the distal end at an angle with respect to thecentral axis 101 of the cannula 100. In a second position, the slidingtube 132 is extended out, temporarily straightening the retractor 112.As illustrated in FIG. 5a, a sliding tube 132, in a first positionencases the retractor 112 up to the point at which the retractor 112curves away from the central axis 101 of the cannula thus allowing theretractor 112 to displace and isolate a target vessel. The proximal endof the sliding tube 132 is linked to button 107 for tanslationallymoving retractor 112 as well as actuating the sliding tube 132. In oneembodiment, as illustrated in FIG. 5a, the sliding tube 132 is in afirst position with the button 107 in an upright position. A spring 134is coupled between a support structure 135 and the proximal end 137 ofthe sliding tube 132. In the first position of sliding tube 132, thespring 134 is extended fully and exerts little or no force on thesliding tube 132. Of course, sliding tube 132 may be manuallymanipulated without linkage to a button 107.

To extend the sliding tube 100, button 107 is pushed down. Asillustrated in FIG. 5b, the button 107 has a cam surface 136 whichpushes on the proximal end 137 of the sliding tube 132 as the button 107is pressed. The sliding tube 132 is pushed forward, overcoming theresilient force of spring 134, to encase the retractor 112 and decreaseangle 117 between the distal end of the retractor 112 and the centralaxis 101 of the cannula 100. Upon releasing the button 107, the springforce urges the proximal end 137 of the sliding tube 132 back toward thefirst position against button 107. The sliding tube 132 is formed ofmaterial having sufficient strength to force the retractor 112 tostraighten out the angle 117, and the retractor 112 is formed ofresilient material having a sufficient flexibility to straighten out theangle 117 in response to a tube 132 being slid over the retractor 112,but having sufficient rigidity to cradle and dissect a target vessel.Resiliency of the retractor 112 ensures return to the downwardly-curvedshape after being released from tube 132. Thus, in accordance with thisembodiment, a user may employ the curved retractor for certainapplications and employ the straightened form for other applications. Amanual actuator may be configured in other ways than button 107 toextend the sliding tube 132 in response, for example, to being pulled upinstead of pushed down.

Another embodiment employs a retractor 112 which has a naturallystraight shape. As illustrated in FIGS. 6a and 6 b, an angling device140 is disposed between the distal end of the retractor 112 and theproximal end of the cannula. The angling device 140 may be positionedwithin the same lumens 113 as the retractor 112 and preferably maycomprise two wires coupled to points below the cradle 116 of theretractor 112 substantially in parallel positions on each of the legs141, 142.

Upon extending the retractor 112 using button 106, the angling device140 is extended with the retractor 112. The angling device 140 iscoupled to a handle 145 at the proximal end of the cannula 100 tofacilitate establishing an angle in the retractor 112 by pulling with abackward force on the angling device 140. As illustrated in FIG. 6b,after the retractor 112 is extended, the angling device 140 is actuatedand a bend is created in the retractor 112 as the backward force exertedon the distal end of the retractor is exerted against the relativelyfixed position of the retractor legs 141, 142 disposed within the lumens113. As shown in FIG. 6c, the angling device 140 may also be located ina separate lumen 202 from the retractor 112 with part of the anglingdevice 140 positioned outside of the cannula 100 when the retractor 112is in the retracted position.

FIG. 7a illustrates another embodiment of cannula 100 in which theretractor 112 is pre-formed with one leg 141 of the retractor 112 bentat an angle at its proximal end skewed to the axis of the distal end ofthe other leg 142. The bent portion of the leg 141 may be linked to asliding knob 147 for convenient manual manipulation of this embodimentof the invention. Upon sliding the knob 147, the leg 142 coupled to knob147 is twisted rotationally. The two legs 141, 142 of retractor 112 arecoupled together via cradle 116. The axis of the second portion of theretractor 112 in the first position is at a first angle 117 to the axisof the cannula 100, as shown in FIG. 7b. As knob 147 is moved, leg 141is rotated and crosses under leg 142, as shown in FIG. 7c. This causescradle 116 to flip 180 degrees and bends the retractor 112 at a secondangle 119, as shown in FIG. 7d. Thus, if a vessel is disposed on oneside of cradle 116 or cannula 100 while the retractor 112 is in thefirst position, then upon rotating the knob 147, the vessel istransported to the other side of the cannula 100. This allows the userto isolate the vessel by simply actuating knob 147.

FIG. 8a illustrates a cut-away side view of button 106 on the handle 104of cannula 100, with an endoscope 126 positioned within cannula 100. Asmentioned above, button 106 is coupled to one leg 141 of the proximalend of retractor 112. Sliding the button 106 in groove 146translationally moves the retractor 112. Groove 146 is preferablyminimally wider than the shaft of button 106 to minimize excessivehorizontal movement of button 106 while still allowing smoothtranslational movement of button 106. As illustrated in FIG. 8b, thebutton 106 may include locking or ratcheting teeth 152 to give tactilefeedback of its location, and to positively retain the button and theassociated leg 141 in an extended or retracted position. Several matingteeth 148 are located underneath groove 146, and a spring member 150 isattached to button 106 to exert pressure against the base of groove 146,to engage mating teeth 148, 152. When a force is applied on the top ofbutton 106, the interlocking sets of teeth are disengaged and button 106can move freely. Upon achieving the desired extension or retraction ofthe leg 141, button 106 is released and is retained place by the engagedteeth 148, 152.

FIG. 9a illustrates a top view of cradle 116 in an embodiment in whichthe cradle 116 is formed by two legs 141, 142 of retractor 112. Thedistal end of the legs form “U”-shaped side guides. The top 144 of thedistal portion of the “U” is preferably flattened. This providesatraumatic support for the target vessel retained within cradle 116.Additionally, by minimizing the thickness of distal portion 144, contactwith other devices in close proximity with retractor 112 is minimized.

The cradle 116 may have other effective shapes, for example, asillustrated in FIG. 9b in which a “C” ring element is attached to legsof the cradle 116. The “C” ring may have a small hole 200 in one sidewith an axis approximately parallel to the axis of the retractor 112.This hole 200 is used to hold suture or other ligating materials, andmay also be used as a knot pusher. As shown in FIGS. 10a and 10 b, in analternate embodiment of the embodiment of FIG. 9b, the retractor 112 isformed and flattened and a “C”-shaped ring is coupled to the retractor112 by, for example, gluing or molding the “C” ring to the distal end ofthe retractor 112, as shown in FIGS. 10c and 10 d.

Referring back to FIGS. 9c, 9 d, and 9 e, the side guides of the cradlemay include a loop 129 in a “V” shape, an arced “U” shape, or asemi-circular shape. In one embodiment, as illustrated in FIG. 9f, theretractor 112 has only one leg 141, and the cradle 116 is formed by theleg 141. A stopper 160 is coupled to the end of the leg 141 to serve asa guide to retain the target vessel, and add a blunt surface to the endof the wire, for example, for pushing and probing tissue. FIG. 9gillustrates a retractor 112 having a spur 204 formed in one or both legs141, 142 for allowing the retractor 112 to be used for dissection.Sinusoidal, half-sinusoidal, and other geometric configurations may beused equally effectively as the shape of loop 129 in accordance with thepresent invention.

FIG. 11a illustrates a tip 1100 for use with a multi-lumen cannulahousing an endoscope. The tapered tip 1100 may be removed from, andreattached to the distal end of a cannula 100, as desired. Uponattachment, the tip 1100 seals the distal end of a cannula 100 in afluid-resistant manner. The tip 1100 is configured to provide dissectionof the tissue surrounding the vessel of interest, and has a distalradius of approximately 0.045″ to reduce the hazard of penetrating thevessel of interest. The inner surface of the tip 1100 tapers to a sharpinterior point and a slightly rounded exterior point and the tip 1100has a uniform wall thickness. The tip 1100 preferably has taper anglesof approximately 15° which provides a maximal, undistorted, visual fieldthrough an endoscope 126. The tip 1100 tapers outward to a maximaldiameter of about 12 mm at its shoulder to cover the cannula 100 bodywhich also has a diameter of about 12¾ mm. All of these features allowthe tip 1200 to effectively dissect tissue. The tip 1100 of FIG. 11a hasa central axis 1150 aligned with the central axis 1108 of the cannula100. The visual field provided by the endoscope 126 is thus more limitedbecause the endoscope 126 is in a lumen that is offset from the centralaxis 1108 of the cannula 100. The endoscope 126 is offset because of thespace required inside the cannula 100 for housing retractors and otherinstruments in adjacent lumens. FIG. 11b illustrates this tip 1100detached from the cannula 100.

FIG. 12a illustrates an offset tip 1200 for a cannula 100 in accordancewith the present invention. The offset tip 1200 is a transparent,tapered tip as described above for use in endoscopic dissection of avessel. However, in this embodiment the axis 1250 of the tip 1200 isskewed relative to the central axis 1108 of the cannula 100. The axis1250 of the tip 1200 is skewed approximately 8°, an angle that is chosento align the apex 1232 of the tip 1200 with a central axis 1112 of theendoscope 126, as shown in more detail in FIG. 12b.

FIG. 12b illustrates the offset tip 1200 housed in cannula 100 in moredetail. The cannula 100 houses a 5 mm endoscope 126 having a centralaxis 1112 eccentric to the central axis 1108 of the cannula 100. Inorder to bring the distal end or apex 1232 of the axis of the taperedtip 1200 into the center of the visual field along the central axis 1112of the endoscope 126, the tapered tip 1200 is tilted or inclined byapproximately 8° toward the lumen housing the endoscope 126. This allowsthe apex 1232 of the tip 1200 to approximately intersect with thecentral axis 1112 of the endoscope 126. As illustrated in FIG. 12b, thetip 1200 is inclined toward the central axis 1112 of the endoscope 126without altering the taper angles 1236 and 1240 of the side walls. Thisis accomplished by forming a transition 1228 between the proximal orcylindrical portion 1204 of the tip 1200 and the distal or conicalportion of the cannula body 1228 of the tip 1200 substantially along aplane 1230 that is skewed from normal to the central axis 1108 of thecanulla 100. The distal portion 1208 of the tip 1200 retains its conicalshape and equal taper angles 1228, 1236 between the side walls and thetransition plane. The slight extension of the cannula body 1228 at thetransition plane provides sufficient incline to allow the apex 1232 ofthe tip 1200 to intersect the central axis 1112 of the endoscope 126.The tip 1200 may be formed of separate conical and cylindrical partsthat are attached together, or the tip 1200 may be formed as anintegrated structure in the shape thus described.

Alternatively, as shown in FIG. 12c, the tip 1200 is inclined at alesser angle, for example, 5 degrees, toward the axis 1112 of theendoscope 126, positioning the axis 1250 of the distal end 1232 of thetip 1200 intermediate between the central axis 1108 of the cannula 100and the axis 1112 of the endoscope 126. Positioning the axis 1250 of thetip 1200 to this intermediate point allows the retention of steepconical angles which allow for easier advancement of the cannula 100while using a minimal amount of force. The intermediate positioning alsoprovides a more complete visual field as seen through endoscope 126.

An alternate embodiment of an offset tip 1200 is shown in FIG. 13 inwhich the taper angles 1320, 1324 of the side walls are selected to formapex 1328 of the tip 1200 aligned with the central axis 1112 of theendoscope 126. As illustrated, the lower region 1316 of the cylindricalpart 1304 extends beyond the upper region 1312 of the cylindrical partat a plane of transition between cylindrical and tapered regions of thetip. However, in this embodiment, the taper angles 1320, 1324 are notequal and the thirty degree angled conical configuration of the taperedpart 1308 is not maintained. Rather, the lower taper angle 1324 isincreased to an obtuse angle and the upper taper angle 1320 is a reducedacute angle relative to the plane of transition between the cylindricaland tapered portions of the tip. In this configuration of the conicalportion 1308, the apex 1328 of the tip 1200 aligns with the central axis1112 of the endoscope 126. Thus, in accordance with either embodiment, atip 1200 is provided which allows a maximal visual field to be viewed bythe surgeon via the endoscope 126 that is eccentric the central axis1108 of the cannula 100, but that is aligned with the apex of the tip1200.

FIG. 14a illustrates a perspective side view of the offset tip 1200 andmounting rod 1404. The tip 1200 is attached to the cannula 100 via thelong rod 1404 which extends through an eccentric lumen of the cannula100, as shown in FIG. 14b, and the apex of the tip 1200 is tilted awayfrom the rod 1404 and towards the endoscopic lumen (not shown). Theelongated rod 1404 may be attached to the tip 1200, or may beconstructed as an integral part of the tip 1200. The elongated rod 1404preferably is secured in housing 1424, shown in FIG. 14c, via threads onthe proximal end of rod 1404 and mating threads 1408 within nut or knob1416. The rod 1404 and housing 1424 abut against the proximal end of thecannula handle 1412, as illustrated in the perspective side view of theassembled device shown in FIG. 14d. Referring back to FIGS. 14a-c, thehousing 1424 includes a slot 1420 configured to slip over the lightcable outlet 1428 on the endoscope 126 as assembled within the cannula100. The housing 1424 preferably contains a rotating nut 1416 whichaccepts the threaded proximal end 1408 of the rod 1404. When tightenedonto the rod 1404, as shown in FIG. 14d, the housing 1424 prevents thecannula 100 from rotating about the endoscope 126 by holding theendoscope 126 fixed with respect to the handle 1412. This allows theoperator to maintain the correct orientation of the endoscope 126 on thevessel. If the endoscope 126 is allowed to rotate freely, the image mayturn sideways or upside down without the operator realizing it, andinjury may occur to the vessel if the cannula 100 is advanced in thewrong direction.

In one embodiment, as shown in FIGS. 14e and 14 f, the elongated rod1404 slips into the housing 1424 via a groove 1450 near its proximalend, and passes through the main hole 1454 in the housing 1424. Thegroove 1450 allows for the housing 1424 to cover the proximal end of themounting rod 1404 without completely clearing the most proximal tip ofthe mounting rod 1404. This allows more room for attaching the housing1424 which lies between the elongated rod 1404 and additional opticalcomponents. The rod 1404 may contain an elastic section, or the rod 1404may be somewhat elastic along its entire length to facilitate stretchingthe rod 1404 and pulling it into position in the slot 1454 on thehousing 1424, while locking the tip 1200 in place. The elastic forcealso facilitates sealing the tip 1200 against the distal face of thecannula body.

FIGS. 15a and 15 b illustrates an alternate embodiment of offset tip1200 and cannula 100. In this embodiment, offset tip 1200 is formed withan elongated case 1500 which slides over the cannula body 100 and locksto the proximal end of cannula 100. In this embodiment, proximal end ofcannula 100 is threaded and allows a threaded proximal section ofelongated case 1500 to mate securely to the cannula 100, which has athreaded proximal end for locking onto the elongated case 1500.

In a surgical procedure using the tissue-dissecting cannula of thepresent invention, the surgeon first incises 1600 the skin overlying avessel of interest to expose the vessel as an initial step of theprocedure illustrated in the flow chart of FIG. 16. A scissor tool isinserted 1602 into the incision to create a path to the vessel bydissecting the overlying tissue. Next, the tip 1200 of the cannula 100is inserted 1604 into the incision to bluntly dissect tissue to form aninitial tunnel along the vessel from the incision. The incision is thensealed 1608 using a blunt tip trocar and a tunnel is insufflated 1612.The cannula is advanced 1616 along the vessel to dissect tissue adjacentthe vessel under endoscopic visualization through the transparent tip.The offset tip 1200 with the apex thereof in alignment with theendoscope 126 provides a full visual field for the surgeon as thecannula 100 is advanced. The conical end of the tip 1200 dissects thetissue as the cannula 100 is advanced along the vessel. The surgeondissects both on the anterior and posterior sides of the vessel tocreate a full 360 degree tunnel around the vessel. Once a selectedsurgical site is reached, the cannula 100 is removed 1620 from theincision seal and the tip 1200 is removed 1624 from the cannula 100. Inone embodiment, as described above, the tip 1200 is removed byunscrewing the threaded portion 1408 of the rod 1404 from the rotatingnut 1416. The tip housing 1424 itself is also removed in thisembodiment. Insufflation is maintained and the cannula 100 without tip1200 is inserted 1628 into the seal into the tunnel adjacent the vessel.Transecting devices are then inserted 1630 in the cannula 100. Withouttip 1200 disposed over the distal end, the cannula 100 can now be usedfor transecting 1632 side branches and the ends of the vessel ofinterest using endoscopic instruments that are selectively installed andremoved within instrument lumens in the cannula body 100. After theseprocedures are completed, the vessel may be removed 1636.

FIG. 17a illustrates another embodiment of an offset tip dilator 1700.In this embodiment of the present invention, the tip 1700 also includeswing-like protrusions for enlarging or dilating a peri-vascular cavityin the course of separating a vessel from adjacent connective tissue.For example, after tissue dissection with an offset tip 1200 to form atunnel or working cavity adjacent a target vessel by dissecting alongthe anterior and posterior sides of the vessel, the cannula 100 isremoved from the distal end of the body, the offset tip 1200 isdetached, and a second tip 1700 is attached to the distal end of thecannula body 100. In one embodiment, the second tip 1700 includes atransparent tapered tip with planar wing-like protrusions or extensionsdisposed proximal to the distal end 1720 of the tip 1700. The wing-likeprotrusions 1702, 1704 each include a swept back leading edge. As shownin FIG. 17b, the tip 1200 is tilted away from the mounting rod 1404 toalign with the central axis of an endoscopic lumen (not shown). Thewing-like protrusions 1702, 1704 may also include curved distal andproximal edges, for example, in a parabolic configuration as shown inFIG. 17c, providing a smoother withdrawal of the cannula 100 from theinsufflated tunnel. The tip 1700 attaches to the cannula body 100 in thesame manner as previously described with reference to the offset tip1200, with an elongated rod 1404 extending through a lumen of thecannula 100 and locking at the proximal end of the handle 1412. Thecannula 100 may thus be advanced through tissue under full-fieldendoscopic visualization through the tapered tip 1720 with the wing-likeprotrusions 1702, 1704 extending substantially diametrically tofacilitate tunnel dilation.

The wing-like protrusions 1702, 1704 of the tip 1700 are arranged insubstantially planar geometry in contrast to the solid bulbous, ovalelement described above. The planar configuration of the wing-likeprotrusions 1702, 1704 substantially reduce the frontal profile of thedilator required to penetrate tissue, and thus reduces the resistiveforce encountered during advancement of the cannula 100 through tissue.Although the tissue-dilating force is exerted on tissue surrounding thecavity in a bilateral, substantially planar orientation by the outeredges of the wing-like protrusions 1702, 1704 that dissect tissueforming the cavity walls, the dilated cavity may retain a roundcross-section for example, within an insufflated cavity, in the samemanner as if tissue dilation was performed using a solid oval dilatorthat applies dilating force circumferentially.

FIG. 18 illustrates a method of dilating tissue in accordance with onemethod embodiment of the present invention. The skin is incised 1800overlying the vessel of interest and the scissor tool is inserted intothe incision to create a path to the vessel by dissecting the overlyingtissue. The incision is then bluntly dissected 1804 using the offset tip1200 to expose the vessel surface. The incision is sealed 1808 and atunnel is insufflated 1812. The cannula 100 is advanced 1816 along thevessel under endoscopic visualization through the transparent tip 1200.After sufficient length of tunnel is formed adjacent the vessel, thecannula 100 is removed 1820 and the incision seal is removed or slidbackwards to the proximal end of the cannula 100. The offset tip 1200 isthen replaced 1824 with the dilating tip 1700. The seal is reinsertedand the incision is sealed 1826. The cannula 100 is advanced 1828 andthe cavity is further dilated responsive to the advancement of theplanar wing-like protrusions 1702, 1704 through tissue forming thetunnel walls. The cannula 100 is removed 1832 a second time, and theincision seal is again removed or slid backwards to the proximal end ofthe cannula 100. The dilating tip is removed 1836 and the incision issealed 1837. Transection devices are loaded 1838 through instrumentlumens within the cannula body 100 into the cannula 100 and the cannula100 is then inserted 1839 back into the incision. Without any tipcovering the distal end of the cannula 100, the vessel side branches andends are transected 1840 using endoscopic instruments, and the vessel isthen removed 1844 from the dilated tunnel.

What is claimed is:
 1. A surgical apparatus for use with an elongatedcannula having an endoscopic lumen for supporting an endoscope, thesurgical apparatus comprising: a transparent tip positioned at a distalend of the cannula, having tapered walls converging toward an apex, theapex having an axis substantially aligned with the central axis of theendoscopic lumen, the endoscopic lumen having a central axis eccentricto a central axis of the cannula, for providing visualization throughthe transparent tip via an endoscope within the endoscopic lumen.
 2. Thesurgical apparatus of claim 1 wherein the tip further comprising: aproximal portion attached to a distal end of the cannula; and a distalportion attached to the proximal portion to form a transition planebetween the proximal and distal portions skewed from the central axis ofthe cannula for positioning the distal end of the distal portion nearthe central axis of the endoscopic lumen.
 3. The surgical apparatus ofclaim 2, wherein the proximal portion further comprises: a cylindricaltube, having an upper region and a lower region, in which a distal endof the upper region extends beyond a distal edge of the lower region;and the distal portion further comprises: a conical end, having an upperand a lower region, in which a proximal end of the lower region extendsproximally beyond a proximal edge of the upper region.
 4. The surgicalapparatus of claim 3 wherein taper angles formed relative to a plane oftransition between the cylindrical tube and the conical end are equal.5. The surgical apparatus of claim 1 wherein the tip further comprises:a cylindrical proximal portion; and a conical end portion, wherein theconical end portion has unequal taper angles relative to a plane oftransition between the cylindrical and conical portions of the tip, foraligning the distal end of the conical portion with the central axis ofthe endoscopic lumen.
 6. The surgical apparatus of claim 1, wherein thetip further comprises: a conical portion, positioned at a distal end ofthe tip; and a mounting rod, attached to a proximal end of the conicalportion, having a locking section disposed at a proximal end of themounting rod.
 7. The apparatus of claim 1 wherein the distal end of thetransparent tip is positioned to align the axis of the distal end withthe central axis of the endoscopic lumen.
 8. A method of dissecting andtransecting vessels using a cannula having a selectively displaceableoffset tip disposed on the distal end of the cannula, the offset tiphaving an axis aligned with a central axis of an endoscopic lumen whichis eccentric to a central axis of the cannula, the method comprising thesteps of: incising skin to expose an area near a target vessel; bluntlydissecting the incision to expose the target vessel; sealing theincision; insufflating a tunnel along the target vessel; and advancingthe cannula through tissue along the target vessel under endoscopicvisualization through the offset tip to form a tunnel in tissue adjacentthe target vessel.
 9. A surgical apparatus for use with an elongatedcannula having an endoscopic lumen for supporting an endoscope, thesurgical apparatus comprising: a transparent tip positioned at a distalend of the cannula, having tapered walls converging toward an apex, theapex having an axis substantially aligned with a central axis of theendoscopic lumen, and in which an elongated optical axis of theendoscopic lumen is eccentric to and substantially parallel to a centralaxis of the cannula, for providing visualization through the transparenttip via an endoscope within the endoscopic lumen.
 10. A method ofdissecting and transecting vessels using a cannula having an offset tipdisposed on the distal end of the cannula, the offset tip having an axisaligned with a central axis of an endoscopic lumen which is eccentric toand substantially parallel to a central axis of the cannula, the methodcomprising the steps of: incising skin to expose an area near a targetvessel; bluntly dissecting the incision to expose the target vessel;sealing the incision; insufflating a tunnel along the target vessel; andadvancing the cannula through tissue along the target vessel underendoscopic visualization through the offset tip to form a tunnel intissue adjacent the target vessel.
 11. A surgical apparatus comprising:an elongated shaft having a longitudinal central axis, a proximal end,and a distal end; and a tissue-dissenting tip attached to said distalend of said shaft and having a tapered portion extending distallytherefrom toward a tissue-penetrating bluntly pointed end that islaterally displaced from said longitudinal axis.
 12. The surgicalapparatus of claim 11 in which the tapered portion of the tipintermediate a proximal end attached to the shaft and the laterallydisplaced tissue-penetrating bluntly pointed end of the tip includesouter surfaces forming a smooth transition between the bluntly pointedend of the tip and the proximal end thereof attached to the shaft. 13.The surgical apparatus of claim 12 in which the elongated shaft includesa lumen for receiving therein an endoscope having an axis of viewingfrom a distal end thereof; and the bluntly pointed tip is disposed inalignment with the viewing axis of an endoscope with the lumen.
 14. Amethod for dissecting tissue along the course of a vessel of interest,comprising: forming a cutaneous incision near the vessel of interest;inserting into the cutaneous incision a tissue-dissecting tip attachedto a distal end of an elongated shaft for penetrating tissue along thecourse of the vessel of enterest, the tip including a proximal endattached to the shaft and including a tapered portion having outerspaces converging distally from the proximal end toward a bluntlypointed tissue-penetrating distal end of the tip that is disposedeccentric a central axis of the elongated shaft; advancing the tipthrough tissue along the course of the vessel of interest; andwithdrawing the elgonated shaft and attached tip through the cutaneousincision.
 15. The method of claim 14 in which the elongated shaftincludes a lumen therein aligned with the bluntly-pointed distal end ofthe tip for receiving in the lumen an endoscope having a viewing angleabout a central axis from a distal end thereof that substantially alignswith the bluntly pointed distal end of the tip for viewing dissection oftissue thereby during the advancement thereof through tissue along thecourse of the vessel on interest.